10/5/2011 9:40 AM PDT

The Las Vegas toy expert often featured on "Pawn Stars" has been named in a police report -- by a woman who claims Johnny Jimenez choked her and held a knife against her throat ... and she tells us, he also threatened to kill her.

Law enforcement sources tell TMZ ... Las Vegas Metro PD received a call from a woman claiming to be Johnny's girlfriend. The woman says she had been in an intense verbal argument with Johnny at his home ... when things escalated and Johnny got physical.

We're told the argument began when Johnny accused the woman of stealing $1,000 from him.

The woman told police Johnny choked her pretty hard -- leaving several marks around her neck and chest. The woman also claims Johnny grabbed a knife at some point in the argument and held it against her throat.

TMZ spoke to the alleged victim who tells us ... Johnny was threatening to kill her during the argument and she feared for her life when Johnny put the knife against her throat.

We're told the woman met with police after the incident -- and filed a formal complaint. An ambulance was also called to check out her injuries.

Police are investigating the incident -- and we're told cops would like to speak with Jimenez ASAP.

TMZ spoke with a staffer at Johnny's toy shop, who tells us the woman was Johnny's housekeeper -- not his girlfriend.

The alleged victim insists she and Johnny have been dating since March -- and claims she was only cleaning his home as a favor.